The armed forces of Libyan strongman Khalifa Haftar said on Thursday that their warplanes had attacked Chadian rebels in the country's southern desert last weekend.

Air raids targeted a rebel-held roadblock 400km (250 miles) southeast of Sebha, as well as other positions in an oasis in the Terbu region 400km farther south, an official with Haftar's so-called Libyan National Army (LNA) told AFP.

"The strikes aim at restoring security and applying law in the south," the official said, without giving details about the identity of the targets.

An armed Chadian group, the Military Command Council for the Salvation of the Republic (CCMSR), said it had been attacked by Haftar's planes.

CCMSR's spokesman in exile, Kingabe Ogouzeimi de Tapol, said there were no casualties.

Chadian President Idriss Deby, he charged, had "subcontracted" Haftar to destroy rebels in Libya who are fighting to overturn the Chadian leader.

CCMSR claims to have several thousand fighters in Chad. It split in 2016 from another anti-Deby group in Libya, the Front for Change and Concord in Chad (FACT), based in Jufra, which is reputedly on good terms with Haftar.

Chad has a long history of revolt by rebels staged from across its borders. Deby and his precedessor Hissene Habre were themselves rebels who seized power by force of arms.

However, rebel groups today are relatively weak and divided, often using trafficking or extortion to raise funds to survive.

Three CCMSR members, including its leader, Hassan Boulmaye, were arrested last October in the fellow Sahel country of Niger.

Haftar, who opposes a UN-backed unity government based in Tripoli, announced the "liberation" of the eastern city of Benghazi last July after a three-year campaign.

Meanwhile, at least eight people, including civilians, were killed on Thursday in a suicide car bombing of a security barricade in the east of Libya, the second such attack in less than a month, local security and hospital sources said.

A suicide attacker exploded his vehicle at a barricade manned by forces loyal to Haftar near the city of Ajdabiya some 840 kilometres (520 miles) from Tripoli, general Fawzi al-Mansouri, a top officer in the local security forces, told AFP.

Eight other people were injured.

"Five people died on arriving at the hospital shortly after the attack," a source at the city's public hospital told AFP.

The three other victims died later of their injuries, the source who requested anonymity said.

"There were civilians among the dead and injured," Mansouri said, adding that no one has yet claimed responsibility.